Various devices have long been applied for clamping small and large parts to facilitate work operations to be performed on the parts. For example, in the building of model airplanes and similar hobbies, it is necessary to clamp parts for gluing, sawing, sanding, etc. Various spring loaded clamps have been employed; however, they are typically limited in that the clamping results from action about an axis spaced from the jaws, and therefore, such clamps do not have parallel jaw surfaces. Screw clamps may be employed, but it is difficult to regulate the amount of force applied to delicate parts, and the adjustment of the clamp is slowed by the fact that it must be rotated many turns to move the jaws to a new clamping position.
Therefore, to obtain a wide adjustability, and parallel clamping jaws, various sliding clamping devices have been proposed. U.S. Pat. No. 2,510,077 is typical of such devices. In this device, the clamping force is transmitted to rods on which the jaw slides, causing a bending action, and therefore, locking the device in position. However, to release the device, it is necessary to straighten the rods and this requires a two-handed operation, and for some sizes, may be difficult for a single individual to accomplish. Since the rods must be made sufficiently flexible to cause the bending engagement, they cannot have sufficient strength to tolerate high clamping pressures and still be easily operated. Lastly, to accomplish clamping at a particular pressure, it may be necessary to initially apply more than that amount of pressure to the jaws, and therefore, to the clamped object. In some instances, the clamped object can be damaged by the excessive forces necessary to set the jaws.
It is, therefore, desirable to have a clamp with sliding jaws where the force necessary to establish the clamping action does not exceed the sustained clamping force. Such a clamp is particularly desired where the clamping force can be sustained over long periods of time.